Environmental assessment of gasification and green hydrogen potential role in waste management decarbonization

Achieving sustainability involves implementing a circular economy model and decarbonizing the waste management sector. The development of innovative technologies that enable the reduction of emissions and resource recovery is one of the sector's greatest challenges. From this perspective, the waste-to-methanol (WtM) process represents a viable prospect, the potential environmental impacts of which have never been studied from a life-cycle perspective. A cradle-to-grave LCA analysis was conducted, studying WtM technology and its potential implementation of green hydrogen (WtM-GH) in the process, through a comparison with traditional waste-to-energy (WtE). The results showed that WtM-GH performs best for global impacts, with a global warming potential of 3.52·10 7 kgCO 2eq instead of 1,04·10 8 kgCO 2eq proper of the WtE. Positive effects take place also for the fossil resource scarcity. Looking for non-toxic regional/local impacts WtE represents the best scenario, with the best performance on water consumption (7.96·10 7 m 3 ) and ionising radiation (2.82·10 7 kBq Co-60 eq ). Cumulative impact results, obtained through the normalization, found that WtM is the best scenario, thanks to the less toxic impact compared to the other two, especially for freshwater ecotoxicity (5.26·10 6 kg 1,4-DCB) and marine ecotoxicity (6.73·10 6 kg 1,4-DCB). WtM-GH allows the production of 1366 kg of methanol per ton of Refuse Derived Fuel, thanks to the conversion of the entire CO 2 contained in the waste, enhancing the value of by-products and carbon credits on the market and making the process more economically sustainable. • The waste-to-methanol process allows a reduction in global impacts, at the expense of regional/local impacts • The waste-to-energy process represents the best option for impacts on a regional scale • Green hydrogen use in waste-to-methanol leads to a notable reduction in global warming, allowing the potential utilization of CO 2 • The energy sources used are a key aspect of waste-to-methanol, whose performance is positive only in the case of low-carbon energy